Revert "serf: requires clt for now"

This reverts commit b275fe46a566ca6d75556f38706fd6ff11f5b145.
Revert "serf: pass build variables"

This reverts commit 8d2d939ae20e5e2bcced909673bd11a9b454d920.
Revert "serf 1.3.0"

This reverts commit 156fd6eefe0272440f2e25a92ff6cfef2e97ca30.